公开(公告)号：DE2965298D1

公开(公告)日：1983-06-01

申请号：DE2965298

申请日：1979-10-31

Applicant: IBM

Inventor： GASTON CHARLES ARDEN ,  KIRK JOSEPH PENNELL ,  WASIK CHESTER ALEXANDER

IPC: G01B11/06

Abstract: An optical system and technique for monitoring a monotonic change in the thickness of a transparent film by means of optical interference, and for eliminating ambiguity in the identification of absolute film thickness. The system is particularly adapted for monitoring the etching of a dielectric film of uncertain initial thickness in microelectronic fabrication. The technique utilizes a white light source directed upon the film. Reflected light, modified by optical interference in the dielectric film, is monitored by photodetectors at two distinct wavelengths. The cyclic patterns of intensity change at the two wavelengths are compared to identify unambiguously the absolute thickness of the film, although the initial uncertainty in film thickness may have corresponded to several cycles of either wavelength pattern alone. To simplify phase comparison of the two cyclic patterns, wavelengths can be selected so that some particular coincidence of extrema in the two signals occurs at a film thickness less than the expected minimum initial thickness, and does not occur at any greater thickness up to and including the expected maximum. Determination of the absolute film thickness in this way permits further tracking of the etching process to the desired end point without overshoot.

公开(公告)号：DE3175884D1

公开(公告)日：1987-03-05

申请号：DE3175884

申请日：1981-09-16

Applicant: IBM

Inventor： BOOTH ROBERT MIDDLETON ,  WASIK CHESTER ALEXANDER

IPC: G01B11/06 ,  H01L21/205 ,  H01L21/302 ,  H01L21/3065 ,  H01L21/66

Abstract: An in situ thickness change monitor for determining thickness change in opaque product material (1), such as silicon, in chamber apparatus, such as reactive ion etching apparatus, operative to produce such thickness change. Reference material (19) having thickness change properties, such as etch rate, correlatable to the product material thickness change properties is deposited upon a substrate (17) having an index of refraction such as to form a monitor exhibiting an optical discontinuity. With the monitor positioned within the chamber with the product material, light directed thereto acts to provide reflected beams producing light having an intensity variation due to interference indicative of the thickness of the reference material. Changes in the thickness of the reference material (d') are correlated to changes in thickness of the product material (d).